<PAGE>   1
                                                                     EXHIBIT 4.2
                                                                  CONFORMED COPY

                                 AMENDMENT NO. 1
                                       TO
                       AMENDED AND RESTATED LOAN AGREEMENT
                       -----------------------------------

                  THIS AMENDMENT NO. 1 (this "AMENDMENT") is made as of December
18, 1996 by and among DAYTON SUPERIOR CORPORATION, an Ohio corporation
("BORROWER"), and BANK ONE, DAYTON, N.A. and BANK OF AMERICA ILLINOIS, in their
individual capacity as Banks and as Bank Agent and Collateral Agent,
respectively, under the following circumstances:

         A.       Borrower and Banks entered into an Amended and Restated Loan
                  Agreement dated as of June 17, 1996 (the "LOAN AGREEMENT").

         B.       Borrower and Banks now desire to amend the Loan Agreement in
                  certain respects.

                  NOW THEREFORE, intending to be legally bound, the parties
hereto agree as follows:

                  SECTION 1.  CAPITALIZED TERMS.  Capitalized terms used and not
otherwise defined herein are used with the meaning set forth in the Loan 
Agreement.

                  SECTION 2. AMENDMENT TO DEFINITION OF "PERMITTED LIENS" IN
SECTION 1.1. The definition of "Permitted Liens" in Section 1.1 of the Loan
Agreement hereby is amended by (i) removing the word "and" at the end of
paragraph (g) of such definition, (ii) replacing the period at the end of
paragraph (h) with "; and" and (iii) adding a new paragraph (i) to such
definition as follows:

                           "(i) Liens which constitute a lessor's interest under
                  a Capitalized Lease with respect to equipment purchased by
                  Borrower for an aggregate purchase price not to exceed Two
                  Hundred Fifty Thousand Dollars ($250,000) and leased by
                  Borrower under Capital Leases to Spec Formliners, Inc., a
                  California corporation."

                  SECTION 3. AMENDMENT TO SECTION 6.4 OF THE LOAN AGREEMENT. The
second sentence of Section 6.4 of the Loan Agreement hereby is amended in its
entirety to read as follows:

                  "Notwithstanding the foregoing, Borrower shall be entitled to
                  guarantee: (i) mortgage loans for employees (not to exceed Two
                  Hundred Fifty Thousand Dollars ($250,000) in the aggregate) on
                  a short-term basis, which are necessary in order to relocate
                  Borrower's employees, and (ii) obligations of Spec Formliners,


<PAGE>   2


Inc., a California corporation, under leases of real property which do
not extend for a term of more than six years and do not provide for rental
payments in excess of Ten Thousand Dollars ($10,000) per month in the
aggregate."

                  SECTION 4. CONSENT AND WAIVER UNDER SECTIONS 6.8 AND 6.9 OF
THE LOAN AGREEMENT. Notwithstanding the provisions of Section 6.8 and 6.9 of the
Loan Agreement, the Banks hereby: (i) consent to the investment by Borrower of
up to a maximum of One Hundred Fifty Thousand Dollars ($150,000) in the capital
stock of, and/or promissory notes issued by, Spec Formliners, Inc., a California
corporation, and (ii) waive any requirement that Spec Formliners, Inc. join in
the execution of the Loan Documents or grant to the Banks any security interest
in any of its assets.

                  SECTION 5. REPRESENTATIONS AND WARRANTIES. In order to induce
Banks to enter into this Amendment, Borrower hereby represents and warrants that
it is in full compliance with all of its duties and obligations under the Loan
Agreement, as amended hereby.

                  SECTION 6.  FURTHER AGREEMENTS.

         6.1.     The execution and delivery of this Amendment is not intended
                  to discharge any obligation of the Borrower due to the Banks
                  under the Loan Agreement.

         6.2.     There is no novation by the execution and delivery of this
                  Amendment.

         6.3.     All the terms and conditions contained in the Loan Agreement
                  and all documents executed in accordance therewith, except as
                  expressly modified herein, shall continue unchanged and remain
                  in full force and effect.

         6.4.     This Amendment shall become effective when it has been
                  executed by the Banks and Borrower.

         6.5.     This Amendment shall be considered an integral part of the
                  Loan Agreement, and all references to the Loan Agreement in
                  the Loan Agreement itself or in any document referring thereto
                  shall, on and after the date of execution of this Amendment,
                  be deemed to refer to the Loan Agreement as amended by this
                  Amendment.

                  IN WITNESS WHEREOF, the parties have caused this Amendment to
be duly executed as of the date first above written.

                                             DAYTON SUPERIOR CORPORATION

                                             By /s/ RICHARD L. BRASWELL
                                                Name: Richard L. Braswell
                                                Title: Vice President Finance

                                       -2-


<PAGE>   3



                                          BANK ONE, DAYTON, N.A.,
                                          individually and as Bank Agent
                                         
                                          By /s/ PAUL A. HARRIS
                                              Name: Paul A. Harris
                                              Title: Vice President & Dept. Mgr.
                                         
                                          BANK OF AMERICA ILLINOIS,
                                          individually and as Collateral
                                          Agent
                                         
                                          By /s/ JOHN E. MANKUS
                                             Name: John E. Mankus
                                             Title: Vice President

                                       -3-